Retractable cord reels have been used in various applications to retractably store various types of cables. Typically, a reel might have a stationary end and a retractable end, the retractable end capable of extension from and retraction back into the reel, and which can be connected to, for example, a battery in an electric vehicle. Using a reel provides convenient storage for the cord. The reel also protects the cord from damage, since it need not be left on the ground. Damage to the cord is reduced. The hazard presented to a user by a damaged electrical cord is also avoided.
The use of a reel has a disadvantage, because the flow of current generates heat in the cord. A larger current tends to generate more heat. One application is a charging station for an electric vehicle. If the user parks his electric vehicle very close to the charging station, or if the vehicle is small, it may not be necessary to unreel more than a short length of cord sufficient to reach the battery connector on the vehicle. As current flows from the charging station to the vehicle, heat will be generated in the cord. Because most of the cord is coiled on the reel, heat cannot escape as readily, and the cord temperature can rise, possibly to the point where the function of the charging station, or the safety of the user, is jeopardized. An additional factor is the lack of experience or knowledge on the part of many vehicle operators.